There is a counter argument, if you continually shift your focus you will never allow your products to get to the point where they're really making money. Reusable stage two might be a year away, BFR five. That's four years of lost revenue.
Thankfully, Falcon 9 is already making money. Reusing stage 2 is an optimization that represents an allocation of capital - capital should generally go to the highest-expected-return uses.
They're already making money; reusable second stage would only increase profit a little.
Weighed against the investment to get a reusable second stage. It may still be logical.